I know it's early but ICE DAMMING' what are the ...

These message board pages are now for archival purposes only. Please visit https://www.nachi.org/forum/ for our most recent forum discussions.

I know it's early but ICE DAMMING' what are the ...

What is the biggest cause of ice damming that you see?
Lack of proper ventilation58%10
Heat escaping into the attic area17%3
Lack of insulation or disturbed insulation11%2
or tell us more please.11%2
Total voters: 17. This poll is closed.
AuthorMessage
Charles R. Crooker

CROOKERHANCOX Home Inspections, Inc.
NACHI Member: Yes
(as of 3/25/07)
NACHI Member
Posts: 104
User: ccrooker
Posted: Sep 29, 2005 10:00 PM       Post Subject:
What is the biggest problem of ice damming when you come across it icon_question.gif Someone has asked me to try and find out what is the biggest cause of ice damming so I am asking the masses icon_idea.gif Thanx
Back to Top
cmccann
NACHI Member: No
(as of 3/25/07)
Very Active Poster
Posts: 1764
Posted: Sep 29, 2005 10:06 PM       Post Subject:

Please Note: This user is a non-member guest and is in no way affiliated with NACHI.
All the above.

--
NACHI MAB!

Back to Top
Larry Kage

Welcome Home Inspection Services, LLC
NACHI Member: Yes
(as of 3/25/07)
NACHI Member
Posts: 1150
User: lkage
Posted: Sep 30, 2005 5:51 AM       Post Subject:
cmccann wrote:
All the above.


Yes, the combination of it all.

--
"I have never met a man so ignorant that I couldn't learn something from him."
Galileo Galilei

Back to Top
Claude Lawrenson

Ontario Home Inspections Inc.
NACHI Member: Yes
(as of 3/25/07)
NACHI Member
Posts: 684
User: clawrenson
Posted: Sep 30, 2005 7:20 AM       Post Subject:
Definitely all of the above!

--
Ontario Home Inspections Inc.

Back to Top
Rob Parker

THAMESPEC Inc. Home Inspection Services/Amerispec home ispection service
NACHI Member: Yes
(as of 3/25/07)
NACHI Member
Posts: 29
User: rparker
Posted: Sep 30, 2005 7:26 AM       Post Subject:
all the above can cause ice damming
Back to Top
Larry Ewens

All Certified Inspection Service Systems
NACHI Member: Yes
(as of 3/25/07)
NACHI Member
Posts: 840
User: lewens
Posted: Sep 30, 2005 8:13 AM       Post Subject:
That wasn't the question. Chuck asked what was the biggest cause of ice daming. The biggest in my never himble opinion is heat escaping into the attic.
Larry

--
Just my usual 12.5 cents

From The Great White North Eh?
NACHI-CAN
www.aciss-brant.com
www.certifiedadulttrainingservices.com/

Back to Top
cmccann
NACHI Member: No
(as of 3/25/07)
Very Active Poster
Posts: 1764
Posted: Sep 30, 2005 9:00 AM       Post Subject:

Please Note: This user is a non-member guest and is in no way affiliated with NACHI.
Sorry Larry, But not one of those is any bigger then the other when they cause the same thing. IMHO.

--
NACHI MAB!

Back to Top
Larry Ewens

All Certified Inspection Service Systems
NACHI Member: Yes
(as of 3/25/07)
NACHI Member
Posts: 840
User: lewens
Posted: Oct 2, 2005 7:56 AM       Post Subject:
Chuck
Think about that. If you don't have heat escaping into the attic you don't have heat melting the snow which turns into water and as it descends to the eaves, freezes and starts to dam. The process continues ad infinitum. Ergo sum, no heat into the attic no ice dam.
Larry

--
Just my usual 12.5 cents

From The Great White North Eh?
NACHI-CAN
www.aciss-brant.com
www.certifiedadulttrainingservices.com/

Back to Top
Claude Lawrenson

Ontario Home Inspections Inc.
NACHI Member: Yes
(as of 3/25/07)
NACHI Member
Posts: 684
User: clawrenson
Posted: Oct 2, 2005 8:47 AM       Post Subject:
Ice dams are the large mass of ice that collects on the lower edge of the roof or in the gutters. As more melting snow (or rain) runs down the roof, it meets this mass of ice and backs up, sometimes under the shingles and into the attic or the house.

Ice damming usually occurs with a significant depth of snow on the roof. If the attic temperature is above freezing, it warms the roof sheathing which melts the snow lying on the shingles. This water runs down the roof until it meets the roof overhang, which is not warmed by the attic and will be at the temperature of the surrounding air. If the air and the overhang are below freezing, then the water will freeze on the roof surface and start the ice dam.

An attic with no insulation will generally not have a problem with ice dams. The heat coming through the attic will tend to melt snow off as it lands and prevent much accumulation. A well-sealed and insulated attic will generally not have ice dams. Like the example of a detached garage, this generally results in a cool roof and no great amount of melting. Ice dams are more frequent if the roof is complicated by many valleys and dormers or there is a large roof overhang.

Ice dams will first show up where there is inadequate insulation or major air leaks. One way to find these locations is to look at the roof with the first heavy frost in fall or light snow. Watch where the snow melts off first and find out what is under that spot on the roof. One common sight in such conditions is a horizontal melt line across the roof of a storey-and-a-half house, where the short kneewall meets the ceiling. Other places would be beneath a roof-ducted exhaust fan or over a leaky attic access hatch. The basic relief for ice damming is to seal all attic air leaks and insulate thoroughly, the same solution as for attic condensation.

Many attics, including those under low-sloped roofs, do not have enough space for adequate insulation at the edge of the attic floor. If soffit insulation requires a baffle to keep a ventilation opening against the sheathing, often there will be only 100 mm (4 inches) of space for insulation. This will tend to melt the snow off just above the over hang and promote ice damming.

Ice dams caused by cathedral ceilings are more difficult. The same principles apply to preventing ice dams; stopping house air leaks, good insulation, perhaps ventilation; but cathedral ceilings are harder to get to. An extensive and expensive ice dam solution is to make the roof impermeable by using a self-sealing membrane under the shingles. Building codes require such membranes on the lower part of the roof in new houses. Note that these membranes do not stop ice dams; they just prevent the water from leaking through the roof sheathing. Ice damming can still create the unsightly ice build-up and possible damage to shingles and gutters, but you may be spared the leakage into the house.

For some older houses with complicated roofs, it may be impossible to completely eliminate ice dams. However, for most houses, the preferred solution is to keep house heat out of the attic, by air sealing and insulating, and avoid weaker alternatives.

--
Ontario Home Inspections Inc.

Back to Top
Charles R. Crooker

CROOKERHANCOX Home Inspections, Inc.
NACHI Member: Yes
(as of 3/25/07)
NACHI Member
Posts: 104
User: ccrooker
Posted: Oct 4, 2005 5:32 PM       Post Subject:
Thanx to all for responding with your views icon_lol.gif
Back to Top
Vern Mitchinson

Home Choice Inspections Ltd.
NACHI Member: Yes
(as of 3/25/07)
NACHI Member
Posts: 48
User: vmitchinson
Posted: Nov 2, 2005 2:36 PM       Post Subject:
When the insulation in the attic is in contact with the roof aheathing the heat transfer melts the snow and ice damn are the result. An air space between the insulation and aheathing is required to carry any heat away before it can melt the show on the roof.
Back to Top
Vern Mitchinson

Home Choice Inspections Ltd.
NACHI Member: Yes
(as of 3/25/07)
NACHI Member
Posts: 48
User: vmitchinson
Posted: Nov 2, 2005 2:37 PM       Post Subject:
That should be sheathing not aheathing.
Back to Top
Charles R. Crooker

CROOKERHANCOX Home Inspections, Inc.
NACHI Member: Yes
(as of 3/25/07)
NACHI Member
Posts: 104
User: ccrooker
Posted: Nov 3, 2005 12:33 AM       Post Subject:
Thanx for the info Vern icon_lol.gif
Back to Top
Larry Willick

CBI Canadian Building Inspections, Ltd.
NACHI Member: Yes
(as of 3/25/07)
NACHI Member
Posts: 149
User: lwillick
Posted: Nov 9, 2005 11:47 AM       Post Subject:
If the attic has at least 14 inches of insulation then free flow turbine spinning vents can be installed on the roof. They aid in keeping heat and humidity out of the attic in the summer months and moisture, etc out in the winter months. It is, however, important to have adequate insulation in the attic and also some soffit/eave venting to allow the correct "chimney type" air flow.
Regardes
larry
Back to Top
Charles R. Crooker

CROOKERHANCOX Home Inspections, Inc.
NACHI Member: Yes
(as of 3/25/07)
NACHI Member
Posts: 104
User: ccrooker
Posted: Nov 9, 2005 8:20 PM       Post Subject:
The vents that I like to tell clients about for the roof instead of the leaky turbines is the Maximum, go to www.ventilation-maximum.com and see them. I was told by the sales rep that 1 of them will do what 3 of the mushrooms do.
Back to Top
Roy Cooke

Roys Home Inspection
NACHI Member: Yes
(as of 3/25/07)
NACHI Member
Posts: 1987
User: rcooke
Posted: Nov 10, 2005 11:47 AM       Post Subject:
lwillick wrote:
If the attic has at least 14 inches of insulation then free flow turbine spinning vents can be installed on the roof. They aid in keeping heat and humidity out of the attic in the summer months and moisture, etc out in the winter months. It is, however, important to have adequate insulation in the attic and also some soffit/eave venting to allow the correct "chimney type" air flow.
Regardes
larry


I am not a lover of turbine and most HIs in this area agree.
They do to good of a job in the wind and end up pulling heat through every electric hole and can even lift the attic access door.
They all also become noisy as they get older then they get very noisy until they seize.
They can leak snow if there in no air movement.
I also agree need lots of soffit vents and 1 sq foot of roof vent for every 300 sq feet of home minimum.
I am satisfied with plain old pan vents.
Back to Top
Larry Willick

CBI Canadian Building Inspections, Ltd.
NACHI Member: Yes
(as of 3/25/07)
NACHI Member
Posts: 149
User: lwillick
Posted: Nov 10, 2005 12:32 PM       Post Subject:
So far we have not had any leaking turbine vents in this area. I must agree though, it is possible with the much higher winds on the east coast if the turbine vents are over taxed by wind forces they could self destruct. So far on the west coast, where the weather is better, we have not had this problem.
Regards
larry
Back to Top